fsurf() not supported

[xarico10]

When using fsurf() to create a surface plot of a function, an error is being printed.

fsurf(@(x,y) sin(x)+cos(y))

fig2plotly(gcf, 'offline', false);

The previous code prints the following error:

Error using response_handler (line 31)
Expecting (x, y) pairs

Error in makecall (line 32)
    response_handler(resp);

Error in plotly (line 28)
response = makecall(args, origin, structargs);

Error in plotlyfig/plotly (line 449)
                response = plotly(obj.data, args);

Error in fig2plotly (line 49)
p.plotly;

Error in untitled5 (line 4)
fig2plotly(gcf, 'offline', false);

Expected plot:

Examples on using fsurf() can be found on:
https://www.mathworks.com/help/matlab/ref/fsurf.html#responsive_offcanvas

[gilbertogalvis]

PR #328 fix this issue